There is a need for a run-flat pneumatic tire having an emergency running capability enabling it to be run on for a certain distance even when the tire rapidly falls in inside pressure due to a puncture, bursting, etc. during the running of an automobile etc. As such a proposal, for example, Japanese Unexamined Patent Publication (Kokai) No. 10-297226 and Japanese PCT National Publication (Tokuhyo) No. 2001-519279 propose technology for attaching a run-flat support (or an insert) on the rims of the inside cavity of a pneumatic tire, which is usable to support a punctured or otherwise damaged pneumatic tire, whereby the run-flat running is possible.
The above run-flat support has a ring-shaped member having an outer circumference used as the support surface. Elastic rings are attached to the two legs thereof so that the support is supported on the rims through the elastic rings. The technology for using this run-flat support does not make any special modifications to the wheel/rims of conventional general pneumatic tires and enables the wheel/rims to be used as they are, and therefore has the advantage of enabling the production, processing, and mounting facilities of conventional pneumatic tires to be utilized as they are.
On the other hand, as an existing method, there is technology reinforcing the sidewalls of tires to enable run-flat running, but this has the problem that sufficient performance cannot be exhibited in tire sizes having large tire sectional heights. Further, as technology for providing a run-flat support at the inside cavity of a tire as explained above, there is one making the insert solid, but this has the problem that, since the insert does not have flexibility, the assembling thereof is difficult. Further, there are also proposals for use of special rim structures or special tire structures, but these have the problems that neither the tires nor the wheels have general usability, and therefore an excessive burden is provided on the user.
On the other hand, the technology using a run-flat support is superior in general usability and assembly, but the bonding strength of the contact surfaces of the elastic rings with the ring-shaped member has a large effect on the durability of the run-flat support and greatly governs the durability thereof. Therefore, to improve the durability of the run-flat support in a tire/wheel assembly having a run-flat support and to increase the run-flat distance, it is necessary to improve the bondability of the metal shell surface with the rubber elastic members of the support and the durability thereof.